In recent years, a magnetic field detection device has come to be used in various applications such as motors, industrial equipment, and automobiles. The magnetic field detection device is a device that has a magnetic field detection element such as a GMR (Giant Magneto Resistive) element or a Hall element and uses the magnetic field detection element to detect a magnetic field generated from a magnetic field source (such as a current and magnet)). PTL 1 discloses an example of the magnetic field detection device using the Hall element.
In the magnetic field detection device disclosed in PTL 1, a magnetic path is constituted by using a magnetic body called C core so as to concentrate the magnetic field generated from the magnetic field source in the magnetic field detection element.
FIG. 30 is a schematic view illustrating an example of the C core. In FIG. 30, the longitudinal direction of the figure indicates the vertical direction, and the lateral direction and depth direction thereof indicate the horizontal direction. As illustrated, a C core 100 is an annular magnetic body having a gap 101 in the middle thereof, and the name of the “C core” is derived from this shape. The C core 100 is disposed so as to surround a magnetic field source 102 (current, in this example). This configuration allows a magnetic field 103 generated from the magnetic field source 102 to concentrate inside the C core 100 and inside the gap 101 (space 104). The magnetic field detection element is provided in the space 104 in which the magnetic field 103 concentrates. The Hall sensor described in PTL 1 is also provided in the space 104.